Control system



y 23, 1964 M. E. JONES ETAL I 3,142,785

CONTROL SYSTEM Filed March 23, 1959 FIG.|

INVENTORS MERTIS E. JONES,

' CARROLE R. MINER. BY

THEIR ATTORNEY.

United States Patent Office 3,142,785 Patented July 28,, 1964 3,142,785 CONTROL SYSTEM Mertis E. Jones, North Syracuse, and Carroll R. Miner,

Liverpool, N.Y., assignors to General Electric Company, a corporation of New York Filed Mar. 23, 1%59, Ser. No. 801,119 7 Claims. (Cl. 317-438) This invention relates to a control system, and more particularly to a control system having a resonant reed device.

Conventional resonant reed devices may be utilized in control circuits where a plurality of circuits are desired to be controlled. For example, a pair of contacts may be associated with each of a plurality of resonant reeds which each responds to a different frequency in accordance with the mechanical resonance of each reed. However, when a given reed is excited by the proper frequency causing it to vibrate, its associated contacts are closed only a portion of the time cycle of the activating frequency. To avoid problems associated with this small closing time, it would be advantageous to have the reed mechanically lock in response to its resonant frequency thereby maintaining its associated contacts closed and allowing the secondary circuit containing these contacts to handle large control currents to operate a device such as a motor.

Furthermore, it would be advantageous to excite and lock the resonant reed by the output of an electron device such as a vacuum tube or a transistor. The resonant reed device could then be remotely controlled by a transmitter which would selectively transmit the desired frequency to'the electron device for controlling a given resonant reed and its associated secondary circuit. As an example of a practical application, each reed could control a different circuit for tuning and/or controlling the volume of a television or radio receiver.

Accordingly, it is an object of this invention to provide a novel control system utilizing a resonant reed relay which is controlled by an amplitude modulated signal.

A further object of this invention is to provide an improved control system in which a resonant reed relay is excited and locked by the output of an electron device to which an amplitude modulated signal is applied.

In carrying out this invention in one illustrative embodiment thereof, an amplitude modulated control signal is applied to an electron device, such as a vacuum tube or a transistor, for detection. The output of the electron device is applied' to the driving coil of a resonant reed relay for providing both an alternating current drive for causing vibration of a reed and a direct current component for causing a locking of the reed.

These and other advantages of this invention will be more clearly understood from the following description taken in connection with the accompanying drawings, and its scope will be apparent from the appended claims.

In the drawings:

FIGURE 1 shows a schematic diagram of the control system embodied in this invention,

FIGURE 2 is a schematic diagram of another embodiment of this invention,

FIGURE 3 is a schematic diagram of still another embodiment of this invention and FIGURE 4 is a schematic diagram of a further embodiment of this invention.

Referring now to FIGURE 1, a carrier signal which has been amplitude modulated by a modulating signal is applied to a triode tube 15 having a cathode 18, a control grid 14 and an anode 16 by a pair of input terminals and 12. The input terminal 10 is connected to the control grid 14 and the input terminal 12 is connected to the cathode 18 which is grounded. A source of bias potential 20 and a biasing resistor 22 are serially connected between the grid 14 and the cathode 18. The anode 16 of the triode 15 is connected through a driving coil 32 of a vibrating reed device, generally referred to with the reference character 30, to the positive terminal of a battery 25. The negative terminal of the battery 25 is connected to ground. The magnitude of the resistance of resistor 22 is adjusted such that the triode 15 is biased approximately at cut-olf. Accordingly, when an amplitude modulated signal is applied to the grid 14, pulses of plate current appear across the driving coil 32 on the positive half-cycles of the amplitude modulated wave, and no current appears on negative halfcycles. The average plate current of the triode 15 is then dependent on the average amplitude of the applied signal thus providing demodulation. An alternating current component exists in accordance with the envelope of the input wave and a direct current component exists due to demodulation.

The resonant reed relay 30 consists of a driving coil 32 wound on a magnet 34 which has a pair of pole pieces 36 and 38. A plurality of mechanically resonant reeds 40, 42 and 44 are secured at one end thereof on a mounting frame 45. Normally, each of the reeds would be provided with a pair of contacts 39 which could be utilized for operating a secondary circuit. In the drawings, only one set of contacts are shown to simplify the drawing. It will also be appreciated that the reed may constitute one of the contacts. Each of the reeds 40, 42 and 44 has a different resonant frequency. When the driving coil 32 is excited by the frequency corresponding to the mechanical resonant frequency of one of the reeds, it causes the reed to vibrate. The reed thus put in vibration would strike its associated contacts 39 from two to twenty percent of the time cycle of vibration. Since such a secondary circuit would only be closed during a small portion of the time cycle, such a circuit could not handle large secondary currents. To avoid the problem associated with the small closing time, the present invention contemplates the mechanical locking of the vibrating reed once it begins vibrating.

This is accomplished by the particular type of drive which is applied to the driving coil 32. By utilizing the bias or plate detector 15, the detector applies the audio signal or AC. component to put the reed in vibration, and also supplies a direct current component due to demodulation of the amplitude modulated signal which holds the reed and its associated contacts closed once vibration begins.

As will be appreciated by those skilled in the art, the invention is not restricted to the use of a bias or plate detector which has been disclosed for purposes of illustration. Any type of non-linear circuit may be provided which functions to furnish both the AC. and DC. components to the driving coil in accordance with an amplitude modulated signal to vibrate and lock the reed once vibration begins.

In FIGURE 2, a separate locking coil 46 which is shunted by an audio by-pass capacitor 48 is shown mounted on the magnet 34 in series with the driving coil 32. In this embodiment the AC. or audio components are applied to the driving coil 32 to vibrate the reed having the corresponding frequency and a separate locking coil 46 is provided which is energized by the direct current component provided by the detector to effectively lock the vibrating reed.

In FIGURE 3, another embodiment is shown in which a separate electromagnet 52 is provided having a locking coil 50 wound thereon and shunted by an audio by-pass capacitor 54. As in the embodiment of FIGURE 2, the

driving coil 32 and the locking coil 50 are serially connected. The operation is the same as in FIGURE 2. The driving coil 32 sets the reed in vibration by the audio currents passing therethrough and the locking coil 50 is energized by the DC; components to lock the reed thereby holdingits-associated contacts in a closed position.

FIGURE 4. shows a further embodiment of the invention which utilizes the separate electromagnet 52 and its associated locking coil 50' as-shown in FIGURE 3. However-, in this embodiment the locking coil 50 is connected to. a contact 5.4 Whichhas a contact 56 associated therewith The contacts 54 and. 56- are adapted to be closed by their associated reed 44. Although only one set of contacts is. shown: forsimplification purposes, it is to be understood that each reed has an associated pair of contacts 54 and 56. A blocking capacitor 58 is connected inseries with the. driving coil 32 which has one end grounded to. prevent the anode potential on tube 15 from being grounded. A resistor 60'is connected between the anode 16 and the battery 25 to supply the anode with a suitable. Bv-lpotential. In operation, the driving coil 32 sets one of its associated reeds into vibration in accordance with the frequency of the audio currents passing therethrough. The contact 56 associated With thevibrating reedengages, contact 54thereby completing the circuit which includes the locking coil 50. The direct current components in the anode circuitof tube 15 how through the locking coil 50 thereby setting up a magnetic field which mechanically. locks the contacts 54 and 56 and the contacts 39' in. the secondary circuit of the reed so activated.

The present system has many applications for remotely controlling equipment in the communications field. For example, a small transmitter could be utilized to send the frequencies corresponding tothe frequencies of the resonant reeds. These signals could bepicked up, detected and applied to the resonant'reed relay for cont'rollingcircuits-to tune radio or television receivers, or to turn them on or off, or to adjust the volume, or to perform all of the enumerated operations.

Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, this invention is not consideredlimited to the examples chosen for pur- V posesiof disclosure and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.

What We claim as newand desire to secure by Letters Patent-of the United States is:

1; A, control system comprising in combination: an electron device; means for applying a carrier signal which has been amplitude modulated by a modulating signal adapted to vibrate at dilferent frequencies; means for applying said alternating current component to said driving means for vibrating one of said plurality of reeds in accordance with the. frequency: of said alternating 4' current component and for applying said direct current component to said driving means for mechanically locking the reed which has been set in vibration by said alternating current component.

2. A control system comprising in combination: an electron discharge device; means for applying a carrier signal which has been amplitude modulated by a modulating signal to said electron discharge device; means for biasing: said electron. discharge device to approximately cut-off for providing an output signal in response to one polarity of positive half-cycles of said carrier signal; said output signal having an alternating current component in accordance with the frequency of said amplitude modulating signal and a direct current component in accordance with the average amplitude of the half cycles-of, said one polarity of the carrier signal; a vibrating, reed device having a. driving means and a. plurality of mechanically resonant reeds driven thereby, means for applying said alternating current component tosaid driving means for vibrating one of said reeds in accordance with thefrequencyof said alternating current component and said direct current component to said driving means for mechanically locking the reed which has been set into vibration by said alternating current component.

3. A. control system comprising in combination: a circuit including means for detecting amplitude modulated waves to provide an alternating current component and adirect current component in accordance with the frequencyand amplitude of modulated andcarrier-signals respectively; said means applying a carrier signal which has been amplitude modulated by a modulating signal to said circuit; a resonant reed device having a driving means and a plurality ofme'chanicall-y resonant reeds; means for applying said alternating'current component to saiddriving means for vibrating one of said. reeds in accordance with the frequency of said alternating current component and said direct current component to said driving means formechanically locking the reed' which has been set into vibration bysaid alternating. current component. v

4. The structure definedin. claim 3 wherein said driving means'includes a. magnetic. circuit havingv a. coil therein.

5'. The structure defined in claim 3 wherein said driv= ingmeans. includes a magnetic circuit having; first, and secondcoils: therein. and: only said second coil conducts said direct current component. 6. The structure. defined in claim 3 wherein; said. drive means. includes. a pair of magnetic. circuits each ofwhich contains a coil and one which responds only to said direct current component.

' Z. The. structure defined in claim 3 wherein said drive means includes one magnetic circuit responsive to said alternating current component for vibrating one of said reeds and another magnetic circuit for mechanically locking. said reed in response to said direct current component.

7 References Cited in the file of this patent UNITED. STATES PATENTS 

1. A CONTROL SYSTEM COMPRISING IN COMBINATION; AN ELECTRON DEVICE; MEANS FOR APPLYING A CARRIER SIGNAL WHICH HAS BEEN AMPLITUDE MODULATED BY A MODULATING SIGNAL TO SAID ELECTRON DEVICE; MEANS CONTROLLING SAID ELECTRON DEVICE IN A MANNER FOR PROVIDING THAT SAID ELECTRON DEVICE DELIVERS AN OUTPUT SIGNAL HAVING AN ALTERNATING CURRENT COMPONENT IN ACCORDANCE WITH THE FREQUENCY OF THE AMPLITUDE MODULATING SIGNAL AND A DIRECT CURRENT COMPONENT IN ACCORDANCE WITH THE AVERAGE AMPLITUDE OF SAID AMPLITUDE MODULATING SIGNAL; A VIBRATING REED DEVICE HAVING A DRIVING MEANS AND A PLURALITY OF VIBRATING REEDS ADAPTED TO VIBRATE AT DIFFERENT FREQUENCIES; MEANS FOR APPLYING SAID ALTERNATING CURRENT COMPONENT TO SAID DRIVING MEANS FOR VIBRATING ONE OF SAID PLURALITY OF REEDS IN ACCORDANCE WITH THE FREQUENCY OF SAID ALTERNATING CURRENT COMPONENT AND FOR APPLYING SAID DIRECT CURRENT COMPONENT TO SAID DRIVING MEANS FOR MECHANICALLY LOCKING THE REED WHICH HAS BEEN SET IN VIBRATION BY SAID ALTERNATING CURRENT COMPONENT. 